The present invention relates to an ion implanter, and especially relates to an ion implanter to implant a high-speed ion into a material to be processed such as a silicon wafer which is prevented from being charged up so as to be processed with high accuracy.
An example of a conventional ion implanter will be explained using FIG. 3 at first.
FIG. 3 is a sectional view showing total construction of the conventional ion implanter. To the ion beam drawn from an ion source 2 is applied a magnetic field in a mass separator 4 to change the direction thereof, so that only the ion species that should be implanted into a wafer 15 arrives at the wafer 15.
Therefore, ions which should not be implanted to the wafer 15, collide with a beam dump 5 or an isolation slit 6 arranged in the mass separator 4 so as to be removed.
The ion beam leaving the mass separator 4 is accelerated to have an energy necessary for being implanted by a post acceleration tube 7, and is introduced to a quadrupole lens section 8.
The beam entering the quadrupole lens section 8 is shaped to have a suitable beam shape for being implanted to the wafer 15.
The ion beam leaving the quadrupole lens section 8, is transmitted to an ion beam deflection section 13 for isolating and removing electrically neutral components after passing through an exit of the mass separator 4, and only the ion components are introduced to the ion implantion room 14 to be implanted to the wafer 15.
An electron gun 18 and a secondary electron supplying plate 19 to generate secondary electrons by the electrons emitted from the electron gun 18 are arranged between the ion beam deflection section 13 and the ion implanting room 14, and the generated secondary electrons are supplied to the wafer 15.
In this way, the wafer 15 is prevented from being charged up, and quality degradation of the wafer 15 caused by particles generated when being discharged or by destruction of the insulation film is prevented.
Recently, the ion implanter, and especially the electron supplying system thereof, has become large and complicated according to increasing of the beam current, and the measurement system for measuring quantity of the implanted ion has become complicated as well. As a result, the ion implanter has become more expensive.
Furthermore, in the ion implanter for producing SIMOX (Separation by IM plant ion Oxygen) substrate, as the temperature of the wafer needs to be kept high, there arises a problem that measurement of the quantity of the implanted ion becomes difficult when used the conventional device. For example, Japanese patent laid-open 9-245705(1997) discloses an example of a conventional ion implanter as stated above.
Moreover, in the ion implanter for large current, as the implanted ion beam current becomes large compared with the conventional device, the wafer implanted with the ions is charged up easily.